Typically, in solid rocket research, strain gages are used to determine forces. However, a unique situation arises in the development of recoilless, projectile launch systems. The systems as designed produce very low average recoil. However, the components of this small recoil are very large positive and negative forces (&gt;2000 lbs) acting over very short times (45 ms). In order to understand recoil in sufficient depth to analyze and control it, the forces acting over the very short times must be understood and modeled. Experimental data are necessary to support the analysis and modeling. A very high frequency response recoil measurement system is required to provide adequate data resolution. To achieve this very high frequency response all components of the recoil stand must be very stiff (i.e. very high spring constant). The components include the force transducer and the mounting/interface mechanism.
The system presented here is designed to determine force responses at high frequency. The transducer used is an impact device which is very stiff and which results in a frequency response of 30 Khz. The transducer is mounted in a very stiff stainless steel fixture. The transducer will only operate under compressive loads and thus it must be preloaded. The preloading is accomplished by stiff stainless steel bolts. This very stiff system provides an overall frequency response much higher than the frequency range of the recoil-thrust response. Thus this system can be used to determine the recoil-thrust response of the propulsion system.
This transducer fixture can be employed to determine thrust and or recoil for any propulsion system in which high thrust, short duration, events occur.